Genome-wide investigation of caffeic acid O-methyltransferases and expression analysis under different abiotic stresses and anthracnose infection in pepper (Capsicum annuum L.)

Abstract

ABSTRACT The caffeic acid O-methyl transferases (COMTs) facilitate the biosynthesis of lignin and play important roles in many processes, including growth, development and response to stresses. Pepper (Capsicum annuum L.) is a major horticultural crop with significant nutritional and medicinal values. Nevertheless, a comprehensive assessment of the COMT genes in pepper and their involvement in drought, salt tolerance and anthracnose resistance remains unestablished. In the present study, 80 pepper COMT genes were identified and classified into four major groups based on domain structure and phylogenetics. Additionally, the sequence analysis, gene structures, and duplication events were analysed. The genes were unevenly distributed across 10 chromosomes, and 10 pairs of tandem and 13 pairs of segmental duplicated genes were detected in the COMT gene family. Examination of cis-acting regulatory elements detected the presence of phytohormone-specific, stress-receptive and light responsive elements in the pepper COMT promoters. Moreover, qRT-PCR analysis revealed significant upregulated expression of CanCOMT48 to drought stress, CanCOMT14 to salinity stress and CanCOMT18 to anthracnose infection by Colletotrichum truncatum, suggesting their important functions in different stresses. Our results provide significant insights into the expression and probable function of selective COMTs which could be used as potential candidate genes for pepper tolerance breeding.